This is a common cause of multiple regional pain and disability, which is commonly associated with medically unexplained symptoms in other systems.
The prevalence in the UK and US is about 2-3%. Although fibromyalgia can occur at any age, including adolescence, it increases in prevalence with age, to reach a peak of 7% in women aged over 70. There is a strong female predominance of around 10:1. Risk factors include life events that cause psychosocial distress such as marital disharmony, alcoholism in the family, injury or assault, low income and self-reported childhood abuse.
Aetiology of Fibromyalgia
Despite intensive investigation, no structural, inflammatory, metabolic or endocrine abnormality has been identified. However, two abnormalities which may interrelate:
Delta waves are characteristic of deep stages of non-rapid eye movement (non-REM) sleep, usually occurring in the first few hours and thought to have an important restorative function. People with fibromyalgia have reduced delta sleep in a pattern distinct from that seen with depression. Furthermore, deprivation of delta but not REM sleep in normal volunteers produces the symptoms and signs of fibromyalgia, supporting fibromyalgia as a non-restorative sleep disorder.
Abnormal peripheral and central pain processing:
A reduced threshold to pain perception and tolerance at characteristic sites throughout the body is characteristic of fibromyalgia. Abnormal central pain processing is suggested by altered cerebrospinal fluid levels of substance P (increased) and 5-HT (5-hydroxytryptamine or serotonin-reduced); reduced basal levels of regional cerebral blood flow in the caudate and thalamus with an augmented processing response on functional MRI; low basal free cortisol and reduction in evening trough of cortisol; and altered descending inhibition via the hypothalamo-pituitary-adrenal and growth hormone somatomedin axes.
Symptoms of Fibromyalgia
- Multiple regional pain
- Marked fatigability
- Marked disability
- Broken non-restorative sleep
- Low affect, irritability, weepiness
- Poor concentration, forgetfulness
Variable locomotor symptoms
- Early morning stiffness
- Swelling of hands, fingers
- Numbness, tingling of all fingers
Additional, variable, non-locomotor symptoms
- Non-throbbing bifrontal headache (tension headache)
- Colicky abdominal pain, bloating, variable bowel habit (irritable bowel syndrome)
- Bladder fullness, nocturnal frequency (irritable bladder)
- Hyperacusis, dyspareunia, discomfort when touched (allodynia)
- Frequent side-effects with drugs (chemical sensitivity)
The pain is characteristically diffuse and unresponsive to analgesics and NSAIDs, and physiotherapy often makes it worse. Fatigue ability, most prominent in the morning, is another major problem and disability is often marked. Although people can usually dress, feed and groom themselves, they may be unable to perform tasks such as shopping or housework. They may have experienced major difficulties at work or even retired because of pain and fatigue.
Examination usually reveals no synovitis or damage, and no overt neurological defect or wasting.
People with other MSK diseases can develop fibromyalgia. Assessment may prove challenging since many of the symptoms could relate to activity of their multisystem disease. Marked discordance between the severity of reported and observed abnormality is an important feature that suggests fibromyalgia, and widespread hyperalgesic tender sites are not explained by polyarticular disease.
Investigations of Fibromyalgia
There are no abnormalities on routine blood tests or imaging, but it is important to screen for other clinically occult conditions that could contribute to some of the symptoms.
Minimum investigation screen in fibromyalgia
- FBC: Anaemia, lymphopenia of SLE
- ESR, CRP: Inflammatory disease
- Thyroid function: Hypothyroidism
- Calcium, alkaline phosphatase: Hyperparathyroidism, osteomalacia
- ANA: SLE
Management of Fibromyalgia
The aims of management are to educate the patient about the condition, to achieve pain control and to improve sleep. Repeat or drawn-out investigation may reinforce beliefs in occult serious pathology and should be avoided.
Low-dose amitriptyline (10-75 mg at night) with or without fluoxetine may help by encouraging delta sleep and reducing spinal cord wind-up. Many people with fibromyalgia, however, are intolerant of even small doses of amitriptyline. There is limited evidence for the use of tramadol, serotonin-noradrenaline (norepinephrine) reuptake inhibitors (SNRIs) such as duloxetine, and the anticonvulsants pregabalin and gabapentin.
A graded increase in aerobic exercise can improve well-being and sleep quality.
The use of self-help strategies and a cognitive behavioural approach with relaxation techniques should be encouraged. Sublimated anxiety relating to distressing life events should be specifically explored with appropriate counselling. There are patient organisations which provide additional information and support.
Prognosis of Fibromyalgia
The prognosis for hospital-diagnosed fibromyalgia is poor. Although treatment may improve quality of life and ability to cope, most people do not lose their symptoms or diagnostic criteria over 5 years. Subjects diagnosed in primary care, or who have sublimated anxiety that can be successfully addressed, may fare better.